"We could see a return to the six-party talks” whenever North Korea gave reason to believe that negotiations could be “productive and conducted in good faith," he said. Six-party talks were last held in Beijing in December 2008.

While Gates's comments may have appeared strong, they did not include a clear call for North Korea to give up its nuclear program as a prelude to renewing six-party talks, which North Korea has called for “with no preconditions.”

However, South Korea has rejected the notion of returning to talks without preconditions. On Friday, Mr. Lee called for US "cooperation" on the North Korean nuclear issue.

Gates's aims in Asia

Gates’s remarks came after fence-mending stops in China and Japan. In three days in China, he sought to reopen communications with military leaders upset by US arms sales to Taiwan. In Japan, he defended the need for the US to keep 49,000 troops in the country for defense against both North Korea and China, which he warned might “behave more assertively toward its neighbors” if US troops were withdrawn.

In South Korea, where the US has 28,500 troops, Gates encountered deeper sensitivities about North Korea after two recent attacks – the sinking of the South Korean navy vessel that killed 46 people and an artillery barrage on a South Korean island in November that killed two South Korean marines and two civilians.

During today's meeting with Lee and Defense Minister Kim Kwan-jin, Gates made a point of satisfying South Korean leaders by saying that diplomatic engagement should begin with talks between North and South Korea. Defense Minister Kim, for his part, said “strong force is the only way to deal effectively” with North.

Former US envoy: 'We need more than talks'

While Gates held his meetings, elsewhere in Seoul former US nuclear envoy Christopher Hill was speaking at a private think tank about past efforts to denuclearize North Korea. Hill, who negotiated with North Korea during the presidency of George W. Bush, insisted that getting the North to do away with its nuclear program remains the top priority.

“We cannot walk away from that,” he said at the forum here. “We really do not have the option of leaving North Korea to have its nuclear weapons.”

Hill defended the record of the six-party talks in getting North Korea to shut down the five-megawatt reactor needed for producing plutonium for warheads but said the North Koreans “lied on their declaration about uranium enrichment.”

“We need more than talks,” said Hill. “The North Koreans have demonstrated they did not deal with the process seriously.”

What will bring South Koreans to the table?

The purpose of talks – which include Russia and Japan as well as the two Koreas, China, and the US – has always been to end the North Korea’s nuclear program, but the sense among many Koreans is that North Korea has no intention of abandoning nuclear weapons. The construction of a new reactor to produce highly enriched uranium for warheads at the North’s main nuclear complex at Yongbyon has convinced South Korean officials that returning to talks will not resolve the issue.

South Koreans cite two conditions under which talks might resume. “North Korea needs to settle the issue of provocations,” says Hahm Chai-bong, director of the Asan Institute for Policy Studies, “and North Korea should go back to previous freezing” of its nuclear program.

Korean officials say, however, that North Korea is increasingly unlikely to give up its nuclear program in the run-up to the April 2012 centennial of the birth of Kim Il-sung, who died in July 1994. Kim’s son and heir, Kim Jong-il, is believed to be anxious to display the country’s strength while grooming his own son, Kim Jong-un.